After years of touring and removing a succession of top boxes and carrying them up to cabins on ferries or up to hotel rooms I bought a new Givi Trekker Outback 52 litre top box last year and decided to invest in one of Givi's T512 inner bags to go with it.
Very well made bit of kit and a perfect fit for the top box ,easy to get out of the top box with a substantial carrying strap and by all accounts fully waterproof and able to be strapped on top of the box if you are short of space ? (it actually includes a couple of substantial bungee cords for just that use ).
Wish I had thought about them years and 4 battered top boxes ago.
They also do them for panniers as well
Very well made bit of kit and a perfect fit for the top box ,easy to get out of the top box with a substantial carrying strap and by all accounts fully waterproof and able to be strapped on top of the box if you are short of space ? (it actually includes a couple of substantial bungee cords for just that use ).
Wish I had thought about them years and 4 battered top boxes ago.
They also do them for panniers as well